Merge tag 'for-linus-4.4-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen bug fixes from David Vrabel:

 - Fix gntdev and numa balancing.

 - Fix x86 boot crash due to unallocated legacy irq descs.

 - Fix overflow in evtchn device when > 1024 event channels.

* tag 'for-linus-4.4-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/evtchn: dynamically grow pending event channel ring
  xen/events: Always allocate legacy interrupts on PV guests
  xen/gntdev: Grant maps should not be subject to NUMA balancing

5 files changed, 121 insertions, 19 deletions

diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index be1d07d59ee9..1bd9510de1b9 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -40,6 +40,11 @@ extern void arch_trigger_all_cpu_backtrace(bool);
 #define arch_trigger_all_cpu_backtrace(x) arch_trigger_all_cpu_backtrace(x)
 #endif
 
+static inline int nr_legacy_irqs(void)
+{
+        return NR_IRQS_LEGACY;
+}
+
 #endif
 
 #endif
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index 23eb450b820b..8e8d30684392 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -7,4 +7,9 @@ struct pt_regs;
 
 extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
 
+static inline int nr_legacy_irqs(void)
+{
+        return 0;
+}
+
 #endif
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 849500e4e14d..524c22146429 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -39,6 +39,7 @@
 #include <asm/irq.h>
 #include <asm/idle.h>
 #include <asm/io_apic.h>
+#include <asm/i8259.h>
 #include <asm/xen/pci.h>
 #endif
 #include <asm/sync_bitops.h>
@@ -420,7 +421,7 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi)
                 return xen_allocate_irq_dynamic();
 
         /* Legacy IRQ descriptors are already allocated by the arch. */
-        if (gsi < NR_IRQS_LEGACY)
+        if (gsi < nr_legacy_irqs())
                 irq = gsi;
         else
                 irq = irq_alloc_desc_at(gsi, -1);
@@ -446,7 +447,7 @@ static void xen_free_irq(unsigned irq)
         kfree(info);
 
         /* Legacy IRQ descriptors are managed by the arch. */
-        if (irq < NR_IRQS_LEGACY)
+        if (irq < nr_legacy_irqs())
                 return;
 
         irq_free_desc(irq);
diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
index 00f40f051d95..38272ad24551 100644
--- a/drivers/xen/evtchn.c
+++ b/drivers/xen/evtchn.c
@@ -49,6 +49,8 @@
 #include <linux/init.h>
 #include <linux/mutex.h>
 #include <linux/cpu.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -58,10 +60,10 @@
 struct per_user_data {
         struct mutex bind_mutex; /* serialize bind/unbind operations */
         struct rb_root evtchns;
+        unsigned int nr_evtchns;
 
         /* Notification ring, accessed via /dev/xen/evtchn. */
-#define EVTCHN_RING_SIZE     (PAGE_SIZE / sizeof(evtchn_port_t))
-#define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
+        unsigned int ring_size;
         evtchn_port_t *ring;
         unsigned int ring_cons, ring_prod, ring_overflow;
         struct mutex ring_cons_mutex; /* protect against concurrent readers */
@@ -80,10 +82,41 @@ struct user_evtchn {
         bool enabled;
 };
 
+static evtchn_port_t *evtchn_alloc_ring(unsigned int size)
+{
+        evtchn_port_t *ring;
+        size_t s = size * sizeof(*ring);
+
+        ring = kmalloc(s, GFP_KERNEL);
+        if (!ring)
+                ring = vmalloc(s);
+
+        return ring;
+}
+
+static void evtchn_free_ring(evtchn_port_t *ring)
+{
+        kvfree(ring);
+}
+
+static unsigned int evtchn_ring_offset(struct per_user_data *u,
+                                       unsigned int idx)
+{
+        return idx & (u->ring_size - 1);
+}
+
+static evtchn_port_t *evtchn_ring_entry(struct per_user_data *u,
+                                        unsigned int idx)
+{
+        return u->ring + evtchn_ring_offset(u, idx);
+}
+
 static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
         struct rb_node **new = &(u->evtchns.rb_node), *parent = NULL;
 
+        u->nr_evtchns++;
+
         while (*new) {
                 struct user_evtchn *this;
 
@@ -107,6 +140,7 @@ static int add_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 
 static void del_evtchn(struct per_user_data *u, struct user_evtchn *evtchn)
 {
+        u->nr_evtchns--;
         rb_erase(&evtchn->node, &u->evtchns);
         kfree(evtchn);
 }
@@ -144,8 +178,8 @@ static irqreturn_t evtchn_interrupt(int irq, void *data)
 
         spin_lock(&u->ring_prod_lock);
 
-        if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
-                u->ring[EVTCHN_RING_MASK(u->ring_prod)] = evtchn->port;
+        if ((u->ring_prod - u->ring_cons) < u->ring_size) {
+                *evtchn_ring_entry(u, u->ring_prod) = evtchn->port;
                 wmb(); /* Ensure ring contents visible */
                 if (u->ring_cons == u->ring_prod++) {
                         wake_up_interruptible(&u->evtchn_wait);
@@ -200,10 +234,10 @@ static ssize_t evtchn_read(struct file *file, char __user *buf,
         }
 
         /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
-        if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
-                bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
+        if (((c ^ p) & u->ring_size) != 0) {
+                bytes1 = (u->ring_size - evtchn_ring_offset(u, c)) *
                         sizeof(evtchn_port_t);
-                bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
+                bytes2 = evtchn_ring_offset(u, p) * sizeof(evtchn_port_t);
         } else {
                 bytes1 = (p - c) * sizeof(evtchn_port_t);
                 bytes2 = 0;
@@ -219,7 +253,7 @@ static ssize_t evtchn_read(struct file *file, char __user *buf,
 
         rc = -EFAULT;
         rmb(); /* Ensure that we see the port before we copy it. */
-        if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
+        if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||
             ((bytes2 != 0) &&
              copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
                 goto unlock_out;
@@ -278,6 +312,66 @@ static ssize_t evtchn_write(struct file *file, const char __user *buf,
         return rc;
 }
 
+static int evtchn_resize_ring(struct per_user_data *u)
+{
+        unsigned int new_size;
+        evtchn_port_t *new_ring, *old_ring;
+        unsigned int p, c;
+
+        /*
+         * Ensure the ring is large enough to capture all possible
+         * events. i.e., one free slot for each bound event.
+         */
+        if (u->nr_evtchns <= u->ring_size)
+                return 0;
+
+        if (u->ring_size == 0)
+                new_size = 64;
+        else
+                new_size = 2 * u->ring_size;
+
+        new_ring = evtchn_alloc_ring(new_size);
+        if (!new_ring)
+                return -ENOMEM;
+
+        old_ring = u->ring;
+
+        /*
+         * Access to the ring contents is serialized by either the
+         * prod /or/ cons lock so take both when resizing.
+         */
+        mutex_lock(&u->ring_cons_mutex);
+        spin_lock_irq(&u->ring_prod_lock);
+
+        /*
+         * Copy the old ring contents to the new ring.
+         *
+         * If the ring contents crosses the end of the current ring,
+         * it needs to be copied in two chunks.
+         *
+         * +---------+    +------------------+
+         * |34567  12| -> |       1234567    |
+         * +-----p-c-+    +------------------+
+         */
+        p = evtchn_ring_offset(u, u->ring_prod);
+        c = evtchn_ring_offset(u, u->ring_cons);
+        if (p < c) {
+                memcpy(new_ring + c, u->ring + c, (u->ring_size - c) * sizeof(*u->ring));
+                memcpy(new_ring + u->ring_size, u->ring, p * sizeof(*u->ring));
+        } else
+                memcpy(new_ring + c, u->ring + c, (p - c) * sizeof(*u->ring));
+
+        u->ring = new_ring;
+        u->ring_size = new_size;
+
+        spin_unlock_irq(&u->ring_prod_lock);
+        mutex_unlock(&u->ring_cons_mutex);
+
+        evtchn_free_ring(old_ring);
+
+        return 0;
+}
+
 static int evtchn_bind_to_user(struct per_user_data *u, int port)
 {
         struct user_evtchn *evtchn;
@@ -305,6 +399,10 @@ static int evtchn_bind_to_user(struct per_user_data *u, int port)
         if (rc < 0)
                 goto err;
 
+        rc = evtchn_resize_ring(u);
+        if (rc < 0)
+                goto err;
+
         rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, 0,
                                        u->name, evtchn);
         if (rc < 0)
@@ -503,13 +601,6 @@ static int evtchn_open(struct inode *inode, struct file *filp)
 
         init_waitqueue_head(&u->evtchn_wait);
 
-        u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
-        if (u->ring == NULL) {
-                kfree(u->name);
-                kfree(u);
-                return -ENOMEM;
-        }
-
         mutex_init(&u->bind_mutex);
         mutex_init(&u->ring_cons_mutex);
         spin_lock_init(&u->ring_prod_lock);
@@ -532,7 +623,7 @@ static int evtchn_release(struct inode *inode, struct file *filp)
                 evtchn_unbind_from_user(u, evtchn);
         }
 
-        free_page((unsigned long)u->ring);
+        evtchn_free_ring(u->ring);
         kfree(u->name);
         kfree(u);
 
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 2ea0b3b2a91d..1be5dd048622 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -804,7 +804,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 
         vma->vm_ops = &gntdev_vmops;
 
-        vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+        vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
 
         if (use_ptemod)
                 vma->vm_flags |= VM_DONTCOPY;